EP2863272B1 - Escapement mechanism for watch movement - Google Patents

Description

The present invention relates to an escapement mechanism for a watch movement, in particular an escapement of the Swiss lever or English lever type. The invention relates more particularly to the optimization of the assembly formed by the plate pin and the fork of the anchor.

The assembly made up of the plate pin and the anchor fork allows the anchor to be released from a tooth of the escape mechanism wheel and the balance wheel thrust. During the impulse, the plate pin, which is linked to the balance, and the fork of the anchor, allow the transmission of energy from the anchor to the balance at each alternation.

A conventional system consists of a so-called "half-moon" circular ankle with part of the circle which is removed to allow the ankle to enter the inside of the range with sufficient security. The fork is in the form of a rectangular notch, the contact surfaces with the ankle being flat.

Depending on the frequency of oscillation of the balance, the amplitude of rotation of the anchor and the position of its axis of rotation, or other dimensions, there is inevitably some slippage between the pin and the fork in conventional systems. The contact surfaces between the fork and the ankle are the same for the release and for the impulse, that is, the pair of contacting surfaces during the disengagement of the first alternation is identical to the pair of contacting surfaces during the first alternation. impulse of the second half-wave. However, a geometry that would be optimized for the undercut function, might not be optimized for pulse function. In conventional systems, the geometry of the pin and fork assembly is therefore not optimized.

The documents WO 2011/121432 , CH 543 757 and FROM 1523856 each describe an anchor whose fork horns include an engaging surface contacting parts of the pin cams having a non-planar geometric profile.

The optimization of the geometry of the contact surfaces between the pin and the fork aims in particular to reduce the friction in order to reduce the wear of the parts, or even to reduce the energy losses to increase the efficiency of the exhaust.

An object of the invention is to provide a precise and reliable watch escapement mechanism over a long period of use.

It is advantageous to provide a very low wear watch escapement mechanism.

It is advantageous to provide a watch escapement mechanism with very low energy consumption and therefore having a high efficiency.

It is advantageous to provide a compact and robust escape mechanism.

Objects of the invention are achieved by a watch escapement mechanism according to claim 1. The dependent claims describe advantageous aspects of the invention.

In the present invention, a watch escapement mechanism for a watch movement comprises an anchor with a fork and a plate device with a peg coupled to a balance, the fork comprising a first horn and a second horn. The pin includes a first cam portion configured to engage an engagement surface of the first horn, and a second cam portion configured to engage an engagement surface of the second. horn. The engagement surfaces contacting the cam portions - that is, the active surfaces - include a non-planar geometric profile, configured to reduce slip during release and pulse functions. Each of the engagement surfaces has a geometric profile defined by a discontinuous function in its first or second derivative.

This makes it possible to better optimize the profiles of the active surfaces on the ankle and also on the fork in order to eliminate or minimize the friction between these organs. We seek to have a rolling movement without sliding between the parts of the ankle and the fork coming into contact.

According to a preferred embodiment, in one direction of rotation of the balance the first horn functions as an input horn and the second horn as an output horn, and in the opposite direction the first horn functions as a horn. exit and the second horn as the entrance horn. However, the invention also extends to escapement mechanisms having a single release and impulse per round-trip cycle of the balance, and in this case one of the horns functions only as an input horn and the 'other only as an exit horn.

According to one embodiment, the engagement surface may comprise a first portion and a second portion, the first and second portions being interconnected by a surface portion not coming into contact with the cam portions of the ankle. The cam surfaces and the engagement surfaces are configured such that the first portion of the input horn engagement surface at least partially performs a function of releasing a pallet from the anchor, and the second portion of the engagement surface of the exit horn at least in part operates a function of the impulse of said anchor vane. In a variant, the second portion of the engagement surface of the inlet horn at least partly also operates a function of disengaging said pallet from the anchor. In a variant, the first portion of the engagement surface of the exit horn at least partly also operates a function of impulse of said pallet of the anchor. This embodiment offers more than possibilities of optimizing the geometric profiles of active surfaces during clearance and impulse operations.

Alternatively, the engagement surfaces comprise two portions, each portion having a geometric profile defined by a continuous function in its first or second derivative, configured so that the first portion of each engagement surface primarily performs a release function. an anchor vane, and that the second portion of each engagement surface primarily operates a function of an anchor vane.

In one embodiment, each of the cam parts of the peg comprises a geometric profile defined by a discontinuous function in its first or second derivative. Alternatively, a portion of the cam portions never comes into contact with the engagement surfaces. Alternatively, the cam portions comprise two portions, each portion having a geometric profile defined by a continuous function in its first or second derivative, configured so that the first portion of each engagement surface primarily performs a release function. an anchor vane, and that the second portion of each engagement surface primarily operates a function of a pulse of an anchor vane.

The geometric profiles of the engagement surfaces and the cam portions of the pin may include at least a portion corresponding to a cog tooth profile.

In one embodiment where the release and the impulse of the pallets from the anchor take place in the two directions of rotation of the plate device, that is to say at each half-cycle of oscillation of the balance, the engagement surfaces of the fork contacting the ankle may be symmetrical about a midplane of the fork. The cam surfaces on one side of the peg may be symmetrical to the cam surfaces on the other side of the peg in order to have identical engagement between the pin and the fork in both directions of rotation of the balance.

In one embodiment, the fork can advantageously be produced by a deposition process such as by photolithography, or by other manufacturing processes used in the semiconductor industry, in a silicon-based material. This makes it possible to obtain profiles of surfaces of complex shapes with great precision.

In an advantageous embodiment, the geometric profile of the engagement surface comprises a gear train profile. The peg can advantageously also include a complementary cog profile.

In a first variant, the cog profile is an involute profile of a circle. This profile can be automatically defined by specifying values of the modulus (for example 0.2) and of the number of equivalent virtual "teeth" that the anchor and the anchor would have (for example respectively 6 and 21) if they were part of a cog.

In a second variant, the cog profile is a profile according to the NIHS standard (Swiss Watch Industry Standard), for example the NIHS 20-25 standard, version 2002.

The ankle can include a conventional shape, such as a half-moon shape. The peg may, however, include other optimized profiles to complement the profile of the engaging surfaces to eliminate or minimize slippage during release and impulse contacts.

• La figure 1 est une vue en perspective schématique d'un mécanisme d'échappement d'un mouvement de montre ;
• La figure 2a est une vue d'une structure fourchette - cheville d'un mécanisme d'échappement ;
• La figure 2b est une vue d'une structure fourchette - cheville d'un mécanisme d'échappement ;
• La figure 3 est un graphique représentant le travail (ou l'énergie) d'abrasion en fonction de l'abscisse curviligne de la surface de la fourchette en contact avec la cheville, illustrant une comparaison pour trois types de géométries : (i) cheville circulaire et fourchette traditionnelle, (ii) profil NIHS et (iii) profil en développante de cercle.
• La figure 4 est un graphique du couple donnée par l'ancre au balancier, résultant de la simulation FEM en régime statique, illustrant une comparaison pour les trois types de géométries : (i) cheville circulaire et fourchette traditionnelle, (ii) profil NIHS et (iii) profil en développante de cercle.
• La figure 5a est une vue d'une structure fourchette - cheville d'un mécanisme d'échappement selon une forme d'exécution de l'invention, dans une première phase d'impulsion ;
• La figure 5b est une vue similaire à celle de la figure 5a montrant une deuxième phase d'impulsion.

Other objects and advantageous aspects of the invention will become apparent on reading the claims, as well as the detailed description of embodiments below, and the accompanying drawings, in which:

• The figure 1 is a schematic perspective view of an escapement mechanism of a watch movement;
• The figure 2a is a view of a fork - pin structure of an escapement mechanism;
• The figure 2b is a view of a fork - pin structure of an escapement mechanism;
• The figure 3 is a graph representing the work (or energy) of abrasion as a function of the curvilinear abscissa of the surface of the fork in contact with the ankle, illustrating a comparison for three types of geometries: (i) circular ankle and fork traditional, (ii) NIHS profile and (iii) involute profile.
• The figure 4 is a graph of the torque given by the balance anchor, resulting from the FEM simulation in static regime, illustrating a comparison for the three types of geometries: (i) circular pin and traditional fork, (ii) NIHS profile and (iii) involute profile.
• The figure 5a is a view of a fork - pin structure of an escape mechanism according to one embodiment of the invention, in a first pulse phase;
• The figure 5b is a view similar to that of the figure 5a showing a second pulse phase.

Referring to the figures, an escape mechanism for a watch movement comprises a wheel 5 with teeth 9, an anchor 7, and a plate device 4 coupled to a balance 2.

The anchor comprises, a fork 13, paddles 17a, 17b, and a rod 15 interconnecting the paddles to the fork. The rod is rotatably coupled to the frame of a movement by means of a pivot 11. The paddles engage the teeth 9 of the wheel which is connected to a power source providing rotational torque to the wheel. One pallet constitutes the entry pallet 17a and the other constitutes the exit pallet 17b. The anchor comprises a dart 27 fixed on the fork by means for example of a pin driven into a fixing hole at the base of the fork. The mechanism shown corresponds to a Swiss lever type escapement. This principle being well known, the conventional elements and their operation will not be described in more detail herein.

The plate device 4 comprises a large plate 6 with a pin 10 and a small plate 8 provided with a notch for the passage of the stinger. The pin 10 comprises on one side a first cam part 12 and on the other side a second cam part 14. In the direction of rotation of the balance illustrated in figures 2a and 2b (first alternation), the first cam part 12 functions as an input cam and the second cam part as an output cam. The balance having an oscillating movement, in the other direction of rotation (second alternation) the functions of the first and second cam parts are reversed.

The fork 13 comprises a first horn 19 and a second horn 21. In the direction of rotation of the balance illustrated in the figures 2a and 2b (first alternation), the first horn 19 functions as an input horn and the second horn as an output horn. In the other direction of rotation (second alternation), the functions of the first and second horns are reversed.

The first cam portion 12 of the peg is configured to engage an engaging surface 23 of the first horn, and a second cam portion 14 is configured to engage an engagement surface 25 of the second horn. The engagement surfaces contacting the cam portions include a non-planar geometric profile.

In a variant, as illustrated in the figures 5a, 5b , the engagement surfaces 23, 25 include a first portion 23a, 25a and a second portion 23b, 25b, the first and second portions being interconnected by an intermediate surface portion 23c not contacting the cam portions of ankle. Each portion of the engagement surfaces can include a geometric profile defined by a continuous function in its first or second derivative. The engagement surfaces can be configured so that the first portion of each engagement surface primarily performs a function of disengaging a pallet from the anchor, and the second portion of each engagement surface primarily performs a function of releasing a pallet from the anchor, and the second portion of each engaging surface primarily performs a function of releasing a pallet from the anchor. pulse of a pallet from the anchor.

In a non-illustrated embodiment, each of the cam parts of the ankle comprises a geometric profile defined by a discontinuous function in its first or second derivative. An intermediate portion of the cam portions never comes into contact with the engagement surfaces. The cam portions may include two portions, each portion having a geometric profile defined by a continuous function in its first or second derivative, configured so that the first portion of each engagement surface primarily performs a function of clearing a pallet. the anchor, and that the second portion of each engagement surface primarily operates a function of the pulse of a pallet of the anchor.

One aspect of this invention is the use of adapted, curved and simultaneously optimized tooth profiles of the active surfaces, i.e. the contact surfaces, the pin and the fork of the anchor. Different types of profile can be adapted to the pegs and fork depending on the point of the escapement and the frequency of the oscillator. Not exclusively, two types of specific cogs can advantageously be used:

1st type of profile: NIHS (figure 2a)

• Nombre de dent pignon (plateau de balancier) = 6
• Nombre de dent roue (ancre) = 21
• Diamètre de tête = 4.704 mm
• Diamètre de pied = 3.5 mm
• Epaisseur de dent = 0.282 mm
• Rayon de l'ogive = 0.4032 mm
• Rayon à fond de dent = 0.1526 mm

By way of example, a so-called NIHS profile defined according to NIHS 20-25, version 2002, can be used for module 0.2 transmission with the following parameters:

• Number of pinion teeth (balance plate) = 6
• Number of wheel teeth (anchor) = 21
• Head diameter = 4.704 mm
• Foot diameter = 3.5 mm
• Tooth thickness = 0.282 mm
• Bullet radius = 0.4032 mm
• Radius at tooth root = 0.1526 mm

2nd type of profile: involute of a circle (figure 2b)

This profile is automatically defined as a function of the modulus (eg modulus 0.2) and the number of teeth of the pinion and the wheel (eg 6 and 21 respectively).

The use of a suitable tooth profile makes it possible to considerably limit the sliding between the two surfaces in contact, in particular at the start of the impulse phase (see figure 3 ). Indeed, the traditional fork / ankle system presents a significant slip at the start of the impulse which explains why the abrasion work (product of the sliding distance by the tangential force in contact) is higher than for the other two. systems (NIHS and involute profiles). Decreasing the sliding distance at the start of the pulse reduces the risk of wear and therefore increases the torque on the escape wheel. In conventional mechanisms, these phenomena limit the evolution of movements. The increase in the energy transmissible via the escapement makes it possible to maintain movements with a higher energy (and therefore a regulating power), for example of the order of 1 mJ, while traditional movements have an energy of the order of 0.1 mJ.

The mechanism according to the invention is particularly advantageous for oscillators with a relatively low frequency, for example less than or equal to 4 Hz, and having a high inertia, for example greater than 10 mg cm2, and / or equipped with a system for shortening the catching the anchor.

The figure 3 illustrates the abrasion work as a function of the curvilinear abscissa of the surface of the fork in contact with the ankle for three types of geometries: (i) circular ankle and traditional fork, (ii) NIHS profile and (iii) profile in involute of circle. In these examples the abrasion work for the NIHS and involute profiles is reduced by a factor of about three at the start of the function compared to the traditional profile. It follows that the energy transmitted to the balance (and therefore the regulating power) can be higher without introducing an additional risk of wear.

The torque applied by the anchor to the rocker, which is linked to the performance is almost equivalent using tooth profiles for the range transmission / ankle while the 1 ^st pulse occurs on a greater angle (cf. Fig. 4 ). In other words, the total energy transmitted to the balance (area under the curve) is greater than or equal using tooth profiles. The results in Fig. 3 and Fig. 4 make it possible to estimate that, by exploiting this invention, the energy (and therefore the regulating power) of a movement could be increased without introducing an excessive risk of wear of the components concerned.

The figure 4 illustrates the torque given to the balance as a function of its position during the first impulse function for the three types of geometries: (i) circular pin and traditional fork, (ii) NIHS profile and (iii) involute profile circle. At parity of torque available on the escape wheel, the optimized profiles make it possible to transmit almost the same torque to the balance but over a higher angular interval (from 1 ° to 3 ° additional). The total energy transmitted to the balance (integrals of the curves) during the first pulse of the first half wave is therefore greater than or equal using these profiles.

3rd type of profile: multi-profile shape (figure 5)

According to one variant, the transmission properties of each of the solutions are used in the pulse phase where they are the most effective. The principle of this third solution is to combine at least two types of profile for the fork but also for the plate peg. Thus, the contact during the first part of the pulse is made on a first type of profile with less sliding and the contact during the second part is made on another profile. In the example shown in figure 5 , the first part of the impulse ( figure 5a ) is carried out for example with an involute type profile of a circle while the second part ( figure 5b ) is carried out with a traditional fork / peg geometry (circular peg and flat fork).

The invention can also be used in escapements with English type anchors, coaxial or other escapements of known types.

The advantages of the invention include a reduction in the risk of wear at the level of the ankle, in particular for systems with rapid anchor-balance adjustment, and the possibility of simultaneously increasing the torque available at the anchor and the angular interval. impulse (thus the energy transmitted to the movement) without increasing the risk of wear.

Reference list

• balance wheel 2
• an escape mechanism 3
• a wheel 5
• tooth 9
• an anchor 7
• pivot 11
• fork 13
• first horn 19 (entrance horn)
• engagement surface 23
• first portion 23a
• second portion 23b
• intermediate portion (discontinuity) 23c
• second horn 21 (exit horn)
• engagement surface 25
• first portion 25a
• second portion 25b
• intermediate portion (discontinuity) 25c
• dart 27
• wand 15
• pallets 17
• entry pallet 17a
• output pallet 17b
• tray device 4
• large tray 6
• ankle 10
• first part of cam 12 (entry cam)
• second cam part 14 (output cam)
• small tray 8

Claims (14)

1. Escapement mechanism (3) for a watch movement including a pallet lever (7) with a fork (13) and a roller device (4) with an impulse pin coupled to a balance (2), the fork including a first horn (19) and a second horn (21), the impulse pin including a first cam part (12) configured to engage an engagement surface (23) of the first horn, and a second cam part (14) configured to engage an engagement surface (25) of the second horn, wherein said engagement surfaces entering into contact with the cam parts include a non-planar geometrical profile, said mechanism, characterized in that each of said engagement surfaces (23, 25) has a geometric profile defined by a discontinuous function in the first or second derivatives thereof.
2. Escapement mechanism according to the preceding claim, wherein at least an intermediate portion (23c, 25c) of the engagement surfaces never enters into contact with the cam parts of the impulse pin.
3. Escapement mechanism according to claim 2, characterized in that the engagement surfaces include two portions (23a, 23b; 25a, 25b), each portion having a geometric profile defined by a continuous function in the first or second derivatives thereof, configured so that the first portion (23a, 25a) of each engagement surface mainly performs the unlocking function of a pallet stone of the pallet lever, and so that the second portion (23b, 25b) of each engagement surface mainly performs the impulse function of a pallet stone of a pallet lever.
4. Escapement mechanism according to claim 1, characterized in that each of said cam parts (12, 14) of the impulse pin includes a geometric profile defined by a discontinuous function in the first or second derivatives thereof.
5. Escapement mechanism according to the preceding claim, wherein at least one portion of the cam parts never enters into contact with the engagement surfaces (23, 25).
6. Escapement mechanism according to claim 4 or 5, characterized in that the cam parts include two portions, each portion having a geometric profile defined by a continuous function in the first or second derivatives thereof, configured so that the first portion (23a, 25a) of each engagement surface mainly performs the unlocking function of a pallet stone of the pallet lever, and so that the second portion (23b, 25b) of each engagement surface mainly performs the impulse function of a pallet stone of the pallet lever.
7. Escapement mechanism according to any of the preceding claims, characterized in that the geometric profiles of the engagement surfaces (23, 25) and of the cam parts of the impulse pin (12, 14) include at least one part corresponding to a gear tooth profile.
8. Escapement mechanism according to the preceding claim, characterized in that the gear profile is an involute to a circle profile.
9. Escapement mechanism according to claim 7, characterized in that the gear profile is a profile conforming to the Swiss watch industry standard (NHIS).
10. Escapement mechanism according to any of the preceding claims, characterized in that the first cam part is symmetrical to the second cam part.
11. Escapement mechanism according to any of the preceding claims, characterized in that the fork and the impulse pin are made of a silicon-based material or silicon derivative.
12. Escapement mechanism according to any of the preceding claims, characterized in that the fork and the impulse-pin are made by a photolithography method or by a LIGA method.
13. Escapement mechanism according to any of the preceding claims, characterized in that the fork and the impulse-pin are made of a nickel-based material.
14. Watch movement including an escapement mechanism according to any of the preceding claims.

Images